The first example of fluorescence of the solid individual compounds of Eu²⁺ ion: EuCl₂ , EuI₂ , EuBr₂

Fluorescence (FL) from Eu²⁺ ion solid individual compounds was observed for the first time using the examples EuCl₂ , EuI₂ and EuBr₂ . Fluorescence was detected at excitation by ultraviolet (UV) light from powdered samples of Eu (II) halides at room temperature (RT) in an argon atmosphere. In air, FL of all Eu²⁺ compounds studied was stable, and intensity persisted for weeks. Depending on the nature of the halide anion and due to a nephelauxetic effect, the position of the maxima in the FL spectra underwent a red shift in the series: EuCl₂ (409 nm) < EuBr₂ (428 mm) < EuI₂ (432 nm). The lifetimes of the excited states of the Eu²⁺ * ions for EuI₂ , EuCl₂ and EuBr₂ were 355, 76 and 54 ns, respectively.